Dinosaurs went extinct about 65 million years ago (at the end of the Cretaceous Period), after living on Earth for about 165 million years. ... (Using this same time scale, the Earth would have formed approximately 18.5 years earlier.)

Are all dinosaurs really extinct?

Of course, not all dinosaurs had the privilege of being the ancestors of the brood that lives today. All of the species that we consider dinosaurs are long extinct, and plenty of lineages went extinct, too. One branch of the dinosaur family produced the oldest common ancestor of all living birds.

What really made the dinosaurs go extinct?

Evidence suggests an asteroid impact was the main culprit. Volcanic eruptions that caused large-scale climate change may also have been involved, together with more gradual changes to Earth's climate that happened over millions of years.